Acoustical board



June 23, 1931.

F. M. DIETZ ACOUSTICAL BOARD Filed Sept. 7, 1929 INVENTOR BY E'mzivlmfiZDie Patented June 23, 1931 UNITED STATES PATENT OFFICE FRANKLIN M. mmz, or HUTCI-IINSONS MILLS, HAMILTON TOWNS IP; MERCER COUNTY, NEW JERSEY, ASSIGNOR, BY MESNE AssIGNMRN rs-rO JOHNS-MANVILLE CORPORATION, OF NEW YORK, N. 'Y., A cORrORArION OF NEW YORK ACOUSTICAL BOARD Application filed September 7, 1929. Serial No. 390,967. g i

of secondary sound phenomena, particularly echoes or reverberations of sound that interfere with satisfactory audition; an aesthetically pleasing appearance; and comparative simplicity and cheapness of manufacture.

For the purposes of my invention, the

board is made with a broken surface, having a multiplicity of recesses, grooves or channels forming a recurrent pattern. Either such a surface absorbs the incident primaryatmospheric waves; or it mutilates the wave front in reflection, so that the reflected waves are inaudible; or it suppresses or mitigates the secondary sound phenomena in some other 1 h the drawings, Fig. I is a plan view of a sheet of acoustical board embodying my invention. 1

Fig. II shows a section through the sheet, taken as indicated by the line II-II in Fig. I; and, v

Fig. III is a view similar to Fig. I illustrating a modification.

As shown in Fig. I, the grooves or channels 5 in the board form a recurrent pattern, consisting of a multiplicity of units 6, preferably polygonal in shape. In the present instance, each major recurrent unit or'element of the pattern is an individually complete regular polygon: i. e., the character of regularity does not (in this example of the invention) depend on any area being regarded as part of more than one unit 6. And not only are the channels or grooves 5 which form the pattern all of the same length, making them simpler and less expensive to cut, but those bounding each major unit 6 of the pattern are prolonged so as to extend into one or more adj acent major units 6,-a feature which facilitates manufacture by allowing long individu= al cuts without sacrificing the total extent of channelling, or entailing the disadvantage of large unbroken areas. 7 r

As shown, the major unit 6 of the pattern is a hexagon, and the channels 5 bounding each such hexagon are prolonged so as to extend into the corners 7 of each adjacent hexagon 6, toward its center. Accordingly, three of the channels 5 intersect andcross each other at each corner 7,--making' a channel pattern consisting of a multitude of six-pointed stars with alternate points of each star con-nected to the points of adjacent stars: i. e., each cut 5' is'common to two of the six-pointed stars,

The, hexagonal pattern gives a very pleasing visual effect combined with acoustical propertiesi f It will-be understood that while I prefer a pattern whose major polygonal units or elements are completely severed, yet the invention is not in its broader aspects limited to such completely severed units. I

' As shown in Fig. II,'the board is of laminated construction, consisting of two thickexcellent nesses 8, 9 secured together by glue, cement 10 or other means. Openings to form the grooves or channels 5 are cut in the sheet 8, and the sheet 9 serves as a backing to close the'bottoms of the openings and support the separate polygons 6 in proper relative positi'ons. The dot and dash lines indicate r0- I tary cutters or saws 11 that may be used to of the sheet 8, so that the ends of the cuts 5 are undercut, as they appear from the front of the finished board. The undercutting augments the sound-deadening effect, since a recess 5 will strike the overhanging wall at its end and be reflected back to the bottom again.

as Vith grooves 5 -99 from what afterward becomes the back side the soundwave reflected from the bottom of Fig. III illustrates a board similar to that of Fig. I, but having the sides of its grooves 5a undercut, as Well as their ends.

Having thus described my invention, I claim:

1. Acoustical board having its surface broken by a multiplicity of channels forming a recurrent pattern of polygonal units, the channels bounding each unit being pro longed into adjacent units.

2. Acoustical board having its surface broken by a multiplicity of channels of substantially the same length forming a pattern of hexagonal units, the channels bounding each unit being prolonged into the corners of adjacent units.

3. Acoustical board having its surface broken by a multiplicity of channels forming a recurrent pattern of hexagonal units, the channels bounding each unit being prolonged both Ways into the corners of adjacent units.

4. Acoustical board having its surface broken by recesses presenting undercut Walls.

5. Acoustical board having its surface broken by channels having overhanging end walls.

6. Acoustical board comprising a sheet with slots therein defining a recurrent pattern, the slots bounding each unit of the pattern being prolonged into adjacent units, and a backing sheet to which the aforesaid sheet is attached affording a bottom for the slots and thus forming channels in the surface of the board.

In testimony whereof, I have hereunto signed my name at Trenton, New Jersey, this 29th day of August, 1929.

FRANKLIN M. DIETZ. 

